The present invention relates to service continuity in computing systems, and more specifically to providing service continuity for certain applications during live kernel updates.
Server workloads may include critical functions that should have high availability rates. Some workloads may be delay tolerant and inherently reliable. For example, workloads that communicate with client devices using transmission control protocol (TCP) are generally inherently reliable, since the protocol requires that a receiving client acknowledge receipt of packets, and transmitters resend packets to the client when acknowledgment messages indicate that a packet was not received. However, some workloads, such as serving multimedia content (e.g., audio and/or video content) on demand or substantially in real time, are not delay tolerant and may be transmitted using protocols that generally do not provide for reliable content delivery (e.g., via the user datagram protocol (UDP), which does not use acknowledgment or retransmission of lost packets).
Generally, operating systems are updated as update packages are released by an operating system provider to address issues reported by customers. While some updates may not affect operating system kernel components, updates to critical parts of an operating system, such as kernel components, kernel extensions, and some libraries, may require that the operating system be restarted in order to apply the update. To reduce downtime caused by rebooting a server to apply operating system kernel updates, live kernel update features can update critical parts of an operating system without requiring the server be rebooted.
Typically, during a live kernel update, an update manager downloads an update package, applies the update package to the operating system, and creates a clone of the operating system. Subsequently, the update manager transitions the server workload (e.g., services that were running and serving one or more client devices) to the cloned operating system, and after the transition, terminates operations by the pre-update operating system.